Coloured transmission electron micrograph of a T-lymphocyte cell infected by Human T-lymphotropic Virus type I (HTLV-I), which causes leukaemia. The leukaemia is adult T-cell leukaemia-lymphoma. Here the cytoplasm of the infected T-cell is at bottom. Virus particles (red) are seen outside the cell membrane, having budded from the cell. The virus has instructed the cell to reproduce more viruses. This leukaemia affects elderly people, most commonly in Japan, the Caribbean & Africa. HTLV-I virus remains latent for years; when active, T- cells increase in the blood and the immune system is unable to fight secondary infections. Magnification: x28,500 at 6x4.5cm size.